NPK deficiency

Phosphorus: look for a dark purple tinge on large, green leaves and a purpling stem.

N, P & K are mobile, so new shoots will be the last parts of the plant affected by a deficiency. Act quickly and you can fix the problem before it gets too serious.

Nitrogen Deficiency

Micro deficiency

All essential micro elements (like iron & calcium) are less mobile.

Once sited, it's tough for plants to move them around to critically low areas. This means, these deficiencies first show on new shoots and leaves, and less so on older or bigger leaves.

Magnesium is the exception. Deficiencies show on the middle to older leaves, which start turning yellow while their veins stay green (interveinal chlorosis). As the deficiency gets worse, brown rusty spots / burnt patches appear on leaves. Fear not! this problem's easiy enough to fix. All you need is a foliar spray of CalMag.

Iron deficiencies will manifest as interveinal colour loss.

Calcium deficiencies will show as necrosis on young leaves. Growing tips will look brown and crispy and you'll get brown, necrotic spots on the middle to older leaves.

Other causes

Other reasons for colour loss include:

Cold nights

Bleaching from the light being too close

Wind burn

Overly warm nutrient solutions (limiting oxygen at the roots)

Over transpiration on leaves

If caused by lack of oxygen at roots, plants will also look droopy and grow very slowly.

If caused by over transpiration, leaves will first lose some sheen, then will start yellowing. A couple of weeks after the damage was done, you'll start to see rust spots.These leaves slowly start to die as the stomata fail to function properly.

Leaf Damage

Take a look at your leaves. How do they look?

Always look at new shoots - they're the best indicator of what's happening right now.

If new shoots are growing well and look healthy, this might be a sign that a previous problems has been overcome.

Drooping leaves

Leaf drooping

18 hours of intense light is very demanding for young plants! You're bound to get some leaf droop, especially in:

pots where oxygen uptake is limited

a hydro system when feed's become too warm

As plants get bigger, they'll naturally get better at dealing with intense lighting. To help keep them healthy in the meantime, manage your nutrient:

Keep the temperature to 18oC - 21oC

Make sure your pH & CF is right (don't overdo pH adjustments)

Keep your oxygen content high in hydro

Leaf loss

As fast-growing, light-loving plants get bigger, they shed large, old leaves. Don't panic - this is normal!

They do this so that they can direct more nutrients to leaves nearer the light, where more energy is produced.

Leaf size

Bigger, wider leaves form in humid environments, under sodium lights.

Slightly smaller, narrower leaves form in dry environments or under fluorescent lights.

If leaves look a bit too small, it might mean you've been overfeeding

Leaf colour

A shiny vibrant green is what you’re looking for here. If plants are too dark and dull, and curl or hook downwards at the tips, it's a sign of overfeeding.

Colour loss on large, older leaves is normal. As your plant gets bigger, they get less light and lose colour as a result. Your plant then replaces these leaves with new growth nearer the light source.

Curling leaves

Leaf shape

Leaf shape is mostly down to genetics.However

If blades are narrow, lack colour, &are under sized or misshapen, there could be an N, P or K deficiency. Increase your feed strength slightly.

Twisting and mutating of new leaves is either unstable genetics, lack of calcium, silicon or (more commonly) excess chlorine. De-chlorinate your tap water in a bucket for at least 12 hours before use.

Yellowing Leaf Tips

This is common and hard to avoid. As long as there are no other symptoms, it is probably a very mild form of wind burn.

Leaf tip curl down

When leaves curl or 'cup' at the tips and the margins, the plant is trying to retain moisture. Any form of downwards curling usually indicates overwatering or overfeeding.

Damping off

Cuttings & seedlings are at risk of damping off when they're in a humid propagator, where the air is still. The bottom of the stem goes soft and watery looking, which can become the beginning of stem rot.

Browning

Normally, you'll get slight browning on your root surfaces. It's hard to avoid, and normally happens towards the end of your cycle.

It often happens if a system that's supposed run 24/7 gets turned off - like bubblers or NFT systems!

Any more than a little bit of browning and you might have root disease.

Brown Roots

Pythium & Other Diseases

If your roots come apart when a gentle amount of pressure is applied and they all look sloppy and off colour, you probably have Pythium or some other form of root disease.

Grow rooms can smell pretty funky! You don’t want any tell-tale odours escaping your tent or home. Odour control is key. To get their aroma, plants release volatile organic compounds (VOCs) into the air. The good news is these can be removed. Here are 6 things you should do.

Growing organically? Biobizz is a must - it's 100% organic and lets you grow as nature intended!
Biobizz was first launched more than 25 years ago. It quickly became the first Dutch nutrient range to be Skal and OMRI certified as fully organic. Today, it holds 7 different organic certifications and is sold in 64 countries worldwide.
Here's everything you need to know about the range.